How to enable Jumbo Frames on vSwitchX

[New_Newbie]

Guys,

Little help needed.

I have Dell 2650 with four NICs (2 x Intel 8254NXX & 2 x Broadcom BCM5703)

ESX3.5 sees them as (from /etc/vmware/esx.conf)

Intel Corporation 8254NXX Gigabit Ethernet Controller (rev 03)

Broadcom Corporation NetXtreme BCM5703 Gigabit Ethernet (rev 02)

There is no problem with enabling Jumbo Frames on "Intel 8254", but cannot do the same on "Broadcom BCM5703", keep getting following error:

esxcfg-vswitch -m 9000 vSwitch2

Unable to set MTU to 9000 the follow uplinks refused the MTU setting: vmnic2

On Broadcom web site Redhat driver for BCM5703 readme file said:

"Some chips do not support jumbo MTUs bigger than 1500"

Apparently mine does support Jumbo Frames: when same PC booted Win2K3 I can ping with 8000 packet size without fragmentation.

Obviously, I’m doing something wrong, or missing something…

Do I need to update driver or do what?

[RenaudL]

Jumbo Frames support for the BCM5703 family of chipsets is indeed disabled on ESX, no driver upgrade will change this fact.

Notice I'm not saying "it doesn't work", but this chipset is likely to blow up with JFs under load. I'm even surprised Win2K3 lets you play with this setting...

[New_Newbie]

RenaudL,

Thanks for the really quick answer.

>I'm even surprised Win2K3 lets you play with this setting...

You may call it play, but this PC and its twin were members of two nodes Win2K3 cluster (shared storage was connected through iSCSI) for more than 2 years. Though, it’s hard to tell now, was BCM5703 really stressed or not.

Then cluster was replaced with never nodes and I got old ones to play with ESX.

Anyway, short answer is "forget about it!", right?

Another question, would it be a problem to use another dual NIC "Intel Corporation 8254NXX Gigabit Ethernet Controller (rev 03)" as vSwitch to provide iSCSI for few guests OS (Win2K3) with Jumbo Frames enabled? For both "play" and "not-heavy loaded production"?

Thank you!

[RenaudL · Accepted solution]

You may call it play, but this PC and its twin were members of two nodes Win2K3 cluster (shared storage was connected through iSCSI) for more than 2 years. Though, it’s hard to tell now, was BCM5703 really stressed or not.

I guess you are implying this setup used JFs for all this time... Weird.

Then cluster was replaced with never nodes and I got old ones to play with ESX.

Anyway, short answer is "forget about it!", right?

Basically, yes: we're just following Broadcom's recommendations here (they're the chipmaker after all), but I don't really know about the specificities of the problems that may arise when using JFs. BCM5703 are old chipsets, it is unlikely we'll ever change anything about them now.

Another question, would it be a problem to use another dual NIC "Intel Corporation 8254NXX Gigabit Ethernet Controller (rev 03)" as vSwitch to provide iSCSI for few guests OS (Win2K3) with Jumbo Frames enabled? For both "play" and "not-heavy loaded production"?

Thank you!

Maybe

Joke aside, I don't know every nic's supported features, so the best thing to do here would be to try it by yourself and see how it goes: if "esxcfg-vswitch -m XXXX" succeeds then you will be good to go.

[New_Newbie]

>I guess you are implying this setup used JFs for all this time... Weird.

Exactly! JF was used from very beginning.

Basically, yes: we're just following Broadcom's recommendations here (they're the chipmaker after all)

Understood. Some BCM5703 chipset revision may blow out, others may hold well. Much easy to disable it completely than deal with unhappy customers!

>if "esxcfg-vswitch -m XXXX" succeeds then you will be good to go.

It did. The real joke is: I need to play with old crap to make decision for future deployments. Second option looks much cheaper and much easier to setup!

Thanks for you answers!